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| author | Ivan Kokshaysky <ink@jurassic.park.msu.ru> | 2008-03-30 15:50:14 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-04-21 04:47:08 (GMT) |
| commit | 884525655d07fdee9245716b998ecdc45cdd8007 (patch) | |
| tree | 975cbf2b5079430240d3496323df1a266be95d27 /kernel/resource.c | |
| parent | d75b305295c38ba9610ff3b2200f7d1989dc55fd (diff) | |
| download | linux-884525655d07fdee9245716b998ecdc45cdd8007.tar.xz | |
PCI: clean up resource alignment management
Done per Linus' request and suggestions. Linus has explained that
better than I'll be able to explain:
On Thu, Mar 27, 2008 at 10:12:10AM -0700, Linus Torvalds wrote:
> Actually, before we go any further, there might be a less intrusive
> alternative: add just a couple of flags to the resource flags field (we
> still have something like 8 unused bits on 32-bit), and use those to
> implement a generic "resource_alignment()" routine.
>
> Two flags would do it:
>
> - IORESOURCE_SIZEALIGN: size indicates alignment (regular PCI device
> resources)
>
> - IORESOURCE_STARTALIGN: start field is alignment (PCI bus resources
> during probing)
>
> and then the case of both flags zero (or both bits set) would actually be
> "invalid", and we would also clear the IORESOURCE_STARTALIGN flag when we
> actually allocate the resource (so that we don't use the "start" field as
> alignment incorrectly when it no longer indicates alignment).
>
> That wouldn't be totally generic, but it would have the nice property of
> automatically at least add sanity checking for that whole "res->start has
> the odd meaning of 'alignment' during probing" and remove the need for a
> new field, and it would allow us to have a generic "resource_alignment()"
> routine that just gets a resource pointer.
Besides, I removed IORESOURCE_BUS_HAS_VGA flag which was unused for ages.
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/resource.c')
| -rw-r--r-- | kernel/resource.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/resource.c b/kernel/resource.c index 82aea81..cee12cc 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -486,6 +486,24 @@ int adjust_resource(struct resource *res, resource_size_t start, resource_size_t EXPORT_SYMBOL(adjust_resource); +/** + * resource_alignment - calculate resource's alignment + * @res: resource pointer + * + * Returns alignment on success, 0 (invalid alignment) on failure. + */ +resource_size_t resource_alignment(struct resource *res) +{ + switch (res->flags & (IORESOURCE_SIZEALIGN | IORESOURCE_STARTALIGN)) { + case IORESOURCE_SIZEALIGN: + return res->end - res->start + 1; + case IORESOURCE_STARTALIGN: + return res->start; + default: + return 0; + } +} + /* * This is compatibility stuff for IO resources. * |